The present invention relates generally to pinch roller-less type reel-to-reel type recorders in which tape drive is implemented by a frictional force generated by the contact of the tape and a capstan. More particularly, the invention relates to a tape drive control system for use with such tape recorders.
Reel-to-reel recorders have been the subject of continued research into improving the mechanical-electrical interface to achieve greater reliability and improved performance. One of the crucial aspects of performance is the requirement that the tape be driven past the heads at an extremely uniform speed and under a fixed predetermined tension to ensure that the head-tape interface is properly maintained. Many systems for achieving these are known, a popular type using pinch rollers to provide contact pressure with a drive capstan. Such systems, while generally effective, tend to stretch the tape and require contact pressure on the sensitive magnetic surface. The use of pinch rollers therefore presents some undesirable problems. In order to overcome these problem, a pinch roller-less type or frictional force drive capstan type has been the subject of study and potential commercial use.
A typical prior art device is shown in FIG. 1 in which a tape 3 fed from a supply reel 9 is wound on a take-up reel 8 through a roller 7, an idler 2, a capstan 1 and a roller 6. The rollers 6 and 7 are rotatably mounted on first ends of arms 4 and 5, respectively. The first ends of the arms 4 and 5 are inwardly biased by springs 11 and 12, respectively, so that the tape 3 passes over the larger part of the peripheries of the idler 2 and the capstan 1. Because the tape 3 is wound around the idler 2 and the capstan 1 in this manner, the frictional force between the tape 3 and capstan 1 and the idler 2 are stabilized and increased. In a pinch roller-less type tape recorder, unlike an ordinary tape recorder, no pinch roller is needed.
One of the requirements of such system is the prevention of slippage between the capstan and the tape because, in this type of system, the frictional force generated by the contact of the capstan and the tape is used as a driving force for the tape. Another requirement is that the tape run be carried out without scratching or damaging the tape surface particularly when the tape is brought into contact with the capstan.